1. Field of the Invention
This invention relates to improvements in a steering system for a vehicle, and more particularly to such an arrangement of the steering system as to allow a steering column horizontally movable and to absorb the displacement stroke of the steering column, in order to effectively absorb an impact of a vehicle occupant at a vehicle collision.
2. Description of the Prior Art
In order to prevent a so-called secondary collision of a vehicle occupant at a head-on collision of an automotive vehicle, a variety of arrangements have been proposed and put into practical use. Such arrangements include a steering column structure in which a steering shaft contracts to absorb an impact energy when a vehicle occupant collides against a steering wheel, and an airbag located inside a steering wheel and adapted to inflate so that the vehicle occupant strikes against the inflated airbag thereby absorbing an impact energy of the vehicle occupant when a head-on collision of the automotive vehicle occurs.
Now, at the vehicle collision, it is usual that a driver seated on a driver's seat generally horizontally move toward the front section of a vehicle body. It is also usual that the steering column is disposed extending obliquely upwardly in a manner to incline relative to a front panel defining a passenger compartment.
Thus, the steering column extends having an axis crossing obliquely the breast section of a driver. Accordingly, when the driver horizontally move toward the vehicle body front section at a vehicle collision, the impact load of the driver develops a component force in the axial direction of the steering column and another component force in the horizontal direction. Under the action of this horizontal component force, when the steering column contracts, a gouging phenomena is made at the contracting section of the steering column thereby affecting an expected energy absorbing effect.
In view of the above, a structure for absorbing and attenuating the horizontal component force of the steering column in the secondary collision has been proposed and disclosed, for example, in Japanese Utility Model Provisional Publication Nos. 60-81069 and 62-155067 in which a bellows type or resilient energy absorbing body is interposed between the steering column and a front panel or dashboard.
However, drawbacks have been encountered in the above-discussed conventional steering systems, in which a space between the steering column and the front panel or the like is small, and therefore a sufficient stroke to absorb the horizontal component force at the secondary collision cannot be obtained even if the energy absorbing body is interposed in the space. Thus, in the conventional steering systems, an effective energy absorbing structure cannot be provided to protect a vehicle occupant upon the secondary collision.